The main benefit of MLV is that there is a large fleet of them, and you could get more for SEPTA without additional hassle. Trying to buy new single level coaches in such a small number for one transit agency seems impractical knowing the financial implications and the time frame for design, testing, and delivery.
My main thing with any new non-MU purchase is i'd like to see both transit spec ACS-64 (main draw would have to be lowered as to not blow up the reading side), and dual modes. Right now there is a big push for expansion, but the problem is there are no wires any of these places, so to even get a feel of rider numbers without the many-years-away time scale of putting wires up (or back up), a purchase of say 10 dual modes would allow for a proper schedule to be developed that balances their use with the express push-pulls and silverliners, and perhaps even frees up some silveliners to restoring, or increasing trains per day on any given route, especially on the PRR & RDG main lines (west trenton, landsdale, trenton, torndale).
How realistic this is, who knows. Lets see how this transportation bill looks like after it becomes law. There may be money for it, there may not be, and even if there is, SEPTA may do something entirely different all together.
Next stop the square, journal square station next!